Children can sometimes play with the conventional electrical outlets and plugs found in the home. In this play, the child can stick his or her fingers, tongue or other body parts near a plug partially inserted into an electrical outlet and make contact with the prongs of the plug, exposing the child to the severe electrical shock of line voltage. Such a shock can injure and possibly kill the child. Adults as well face a shock hazard when using conventional electrical plugs in the home, e.g., when inserting a plug into a receptacle by touch in the dark or around an obstacle. Many devices have been developed to protect children and adults from these hazards.
In U.S. Pat. No. 4,531,800 to Avener, a device is attached to an electrical outlet and plug to prevent children from pulling out the plug. The invention of this patent is believed to be effective but requires the installation of a special wall receptacle or receptacle cover plate. In U.S. Pat. No. 3,982,084 to Cooperstien, a specially modified electrical receptacle is described wherein electrical contact with the prongs of the plug is not made until the plug is fully inserted into the receptacle. The invention of this patent is also believed to be effective but requires the installation of a special receptacle and the use of a non-standard plug having an additional non-conducting prong which cooperates with the special receptacle. U.S. Pat. No. 4,340,267 to Nakuga, describes a plug having a spring-loaded prong covering member. The prongs of the plug extend through the prong covering member exposing a shortened section of the tip of each prong. When the plug is inserted into a receptacle, the prong covering member is automatically retracted in such a way that the exposed portions of the prongs are covered when the plug is partially inserted into the receptacle. The invention of this patent does not require the replacement of the standard household electrical receptacle and is believed to be effective. However, its construction involves a number of parts which is believed to increase its cost of manufacture.